Portman Square, built in 1764, catered to and drew in very wealthy families. It is known as one of the most beautiful and biggest squares in London. In 1822 there were approximately 15 members of the nobility living there. At this time, it was one of the most distinguished neighborhoods in London. http://www.british-history.ac.uk/old-new-london/vol4/pp406-441

At this time it was not unusual for women to go to London or other urban settings for access to different experiences. They offered many opportunities for new social interaction and there is ample evidence of women traveling to London and partaking of its many social activities. There were also many opportunities of new experiences for pleasure and excitement, some through social interaction. http://www.bbc.co.uk/history/trail/victorian_britain/women_out/urban_life_04.shtml

"To potter about; to move or work in a desultory, ineffective, or dawdling way" (OED).

Meaning enormously.

"A plan; a combination of various things into one view, design, or purpose; a system" (Johnson).

Short for 'post-chaise', defined as ""a horse-drawn, usually four-wheeled carriage (in Britain usually having a closed body, the driver or postilion riding on one of the horses) used for carrying mail and passengers, esp. in the 18th and early 19th centuries"" (OED).

"Constitution or habit of mind, disposition, temperament; ‘nature’" (OED).

The tradesmen or middle sort are below Gentry and make their money by working. They could have as much or more money than the gentry class in some cases, but their status was always considered as lower.

http://www4.wittenberg.edu/academics/hist/crom/brit/socstruc.html